Flower Math by DOTDAY

Plan the beds. Count the plants. Order the right fabric.

A plant spacing calculator built for growers. Enter your beds and spacing, and get rows, plants per row, holes to burn, and a fabric roll list sized by linear feet, not square feet. Print the plan or share it with your crew.

Free, no sign-up · Feet or metric · Printable plan and burn template

Rows of dahlias on a cut-flower farm at sunset, drip line and support stakes along each bed
5 rows in a 4 ft bed at 9 in
01

Plan details

Units
02

Planting beds

One card per bed shape. Use the count for identical beds. Pick a crop to load a typical spacing, then adjust for your variety.

330 plants · 5 rows x 66
Spacing grid
Bed 1 · 5 rows · 330 plants50 ft4 ft
Plan view, not to scale between beds. Hole positions indicative.
03

Fabric

Fabric is bought by the linear foot of roll, not by area. Each bed is a run of roll width; a bed wider than the roll takes another pass with a seam.

3.2oz woven weed barrier. Built for planting beds under mulch, straw, or bare ground: burn holes, plant through, pin the edges.

How this was calculated

Bed 1: cover 6 ft wide on a 3 ft roll = 3 passes with 6 in overlap; each run 51 ft x 1 run = 153 ft.

Cut total 153 ft + 10% waste = 168.3 ft. Roll length 300 ft, so 1 roll (300 ft supplied, 131.7 ft left over).

Area shortcut, for contrast: 200 sq ft of beds divided by 900 sq ft per roll = 0.22 rolls. It ignores passes, overlap, anchoring, and offcuts.

Need drainage under the beds or a French drain alongside? That is a different fabric: see TERRA non-woven geotextile or take the Fabric Finder.

04

Burn template

A printable jig for Bed 1. Burn holes with a propane torch or a hole burner through the jig; the melted edge seals the weave so it will not fray.

Plot planner

Draw the plot. It counts the plants and picks the fabric.

Every square is one foot. Paint beds, paths, patios and drains, and each surface carries the DOTDAY fabric that ground condition calls for. Beds show their real hole layout, so what you see is the burn template.

  • Lawn or clear → no fabric
  • Planting bed → SHIELD
  • Gravel path → XBAR
  • Pavers or patio → XBAR
  • French drain → TERRA

24 × 16 ft384 one-square-foot cells · 7 zones

Drag to paint planting bed. Right-click clears a square.

024681012141618202202468101214Bed A · DahliasPath 1Sitting areaBed B · ZinniasBerry bed · StrawberriesBed C · Snapdragons
Zones
Roll list

What to order

ProductRollQtyEachLine
SHIELDSHIELD 3.2oz woven3 ft × 300 ftWB32SNZ3X3001$84.49$84.49
XBARXBAR 5oz dual-layer woven3 ft × 250 ftWB05SNZ3X2501$114.99$114.99
TERRATERRA 4oz non-woven needle-punched geotextile3 ft × 50 ftGT04SNZZ3X501$69.99$69.99
Estimate before shipping and tax$269.47
Burn sheet

One template per bed

  • Bed A · Dahlias

    12 × 4 ft bed · 3 rows on 18 in · 12 per row on 12 in

    36 holes · first hole 6 in from the edge, 6 in from the end · SHIELD strip 6 ft × 13 ft

  • Bed B · Zinnias

    12 × 4 ft bed · 5 rows on 9 in staggered · 15 per row on 9 in

    73 holes · first hole 6 in from the edge, 6 in from the end · SHIELD strip 6 ft × 13 ft

  • Berry bed · Strawberries

    8 × 8 ft bed · 8 rows on 12 in · 8 per row on 12 in

    64 holes · first hole 6 in from the edge, 6 in from the end · SHIELD strip 10 ft × 9 ft

  • Bed C · Snapdragons

    12 × 4 ft bed · 7 rows on 6 in · 23 per row on 6 in

    161 holes · first hole 6 in from the edge, 6 in from the end · SHIELD strip 6 ft × 13 ft

The method

Why the plus one matters

Plants sit at points, not in areas. A row with spacing s over a usable length L holds floor(L / s) + 1 plants: one at the start, then one every s. Rows across the bed follow the same rule. Area math forgets the first plant in every row and every bed. One burned hole per plant, so the plant count is also the holes count you hand to whoever runs the torch.

Rows across the bed

Usable width is the bed width minus an edge margin on each side. Rows = floor(usable width / row spacing) + 1. A 4 ft bed with 6 in margins at 9 in spacing holds 5 rows, not 4.

Plants along the row

Usable length is the bed length minus an end margin at each end. Plants per row = floor(usable length / plant spacing) + 1. Fifty feet at 9 in gives 66 plants, not 65.

Staggered rows

Offsetting alternate rows lets the row pitch tighten to 0.866 x spacing (an equilateral triangle). Every second row starts half a space in and holds one plant fewer.

Worked example

Four beds, 4 ft by 50 ft, on a 9 in grid

The default plan in the calculator. Margins 6 in at the edges and ends, no stagger.

Step
Result
How
Usable width
36 in · 48 in bed minus 6 in each side
width - 2 x edge margin
Rows
5 · floor(36 / 9) + 1
plus one for the first row
Usable length
588 in · 600 in minus 6 in each end
length - 2 x end margin
Plants per row
66 · floor(588 / 9) + 1
plus one for the first plant
Per bed
330 · 5 rows x 66 plants
holes to burn per bed
Four beds
1,320 · 330 x 4
plants, holes, and plugs to order
Counting gaps instead
1,040 · 4 rows x 65 x 4 beds
280 plants short

The gap-counting shortcut is the one most spreadsheets make. It drops one row and one plant per row in every bed, and the error grows with the number of beds.

Fabric is a strip, not a sheet
Landscape fabric comes on rolls of fixed width. A 4 ft bed with a 12 in anchor allowance each side needs a 6 ft cover, which is one pass of a 6 ft roll or two passes of a 4 ft roll with a seam. The calculator counts passes, seam overlap, end allowance, and cutting waste, then turns linear feet into whole rolls. Square footage alone will leave you short on the last bed.
Spacing grids

Four grids cover most of what you will grow

6 x 6 in

Single-stem sunflowers, stock, snapdragons, tulips, ranunculus and anemones on tight pitch. Dense canopy, high stem count per bed, more holes to burn.

9 x 9 in

The cut-flower workhorse: zinnias, cosmos, celosia, strawflower, gomphrena, scabiosa, marigold. A good default when you are unsure.

12 x 12 in

Branching plants that want room: amaranth, statice, rudbeckia, yarrow, phlox, most vegetables. Dahlias run 12 in the row at 18 in between rows.

18 x 18 in and wider

Nursery stock, lavender, roses, peonies. Fewer plants, larger holes, and a longer life for the fabric between replantings.

Fewer weeds. Cleaner rows. Less labor.

What the numbers become once the fabric is down

Fabric choice

Which fabric goes under a planting bed

Choose by what the fabric sits under, not by weight alone.

Job
Fabric
Why
Planting beds, mulch or bare
SHIELD 3.2oz woven · Burn holes, plant through, pin the edges.
Blocks light, lets water and air through
Beds and paths, one sheet
XBAR 5oz dual-layer woven · Woven top over a needle-punched backing.
Walked paths and wheel lanes wear harder
Gravel paths between beds
XBAR 5oz dual-layer woven · Built for gravel, rock, and traffic.
Puncture resistance under stone
Drainage or French drain
TERRA non-woven geotextile · Filtration and separation, not weed control.
Different job, different fabric

Not sure? The Fabric Finder asks one question about what goes on top and points you to SHIELD, XBAR, or TERRA.

Plants per 4 ft bed, at a glance

Bed length6 x 6 in9 x 9 in12 x 12 in18 x 18 in
25 ft34316510051
50 ft69333020099
75 ft1,043495300150
100 ft1,393665400201
150 ft2,093995600300
200 ft2,7931,330800399
300 ft4,1931,9951,200600
On the ground

Things that change the number once you are outside

Burn, do not cut

A torch or hole burner melts the edge of the weave so the hole cannot run. Cut holes fray and widen over a season, and weeds follow the gap.

Irrigation goes down first

Lay drip tape or line along each row before the fabric. Burned holes then land over the emitters, and the fabric keeps the tape shaded and in place.

Anchor every edge and seam

Pin at the edges and down both sides of each seam. A 12 in allowance past the bed gives the pins something to hold, which is why the calculator adds it.

Plant spacing and fabric, answered

How do I calculate plant spacing for a raised bed?

Subtract the edge margin from each side of the bed width, divide by the row spacing, round down, and add one for the rows. Do the same with the bed length, the end margin, and the plant spacing for plants per row. Multiply the two. The calculator above does this per bed and sums every bed in the plan.

Why does the calculator add one plant to every row?

Because plants sit at points. A 588 in usable length at 9 in spacing has 65 gaps but 66 plants: one at the start, then one after every gap. Skip the plus one and a four-bed plan comes up 280 plants short.

What spacing should I use for zinnias, dahlias, or sunflowers?

Typical intensive spacing is 9 x 9 in for zinnias, 12 in in the row by 18 in between rows for dahlias, and 6 x 6 in for single-stem sunflowers. Pick the crop in the calculator to load a starting grid, then adjust for your variety and climate.

Should I stagger the rows?

Staggering fits about 13% more rows across the same bed width by tightening the row pitch to 0.866 x spacing. It suits crops that want airflow on all sides. The trade is a slightly more awkward burn pattern, which the template handles.

How much landscape fabric do I need for my beds?

Size it by linear feet of roll, not square feet. Each bed is a run of roll width, plus an end allowance; a bed wider than the roll takes extra passes with a 6 in overlap. The roll list in the calculator shows rolls, seams, and offcut for every size DOTDAY sells, using current list prices.

Which DOTDAY fabric is right for planting beds?

SHIELD 3.2oz woven for beds under mulch, straw, or bare ground. XBAR 5oz dual-layer woven when the same sheet runs across walked paths or gravel lanes between beds. TERRA is a non-woven drainage geotextile and is not a weed barrier.

How do I burn holes in weed fabric?

Use a propane torch with a hole-burning tip or a purpose-made hole burner, over a plywood or cardboard jig cut to your grid. Work in dry conditions with water nearby. The melted edge seals the weave so it will not fray. Print the burn template at 100% and check the 6 in bar with a tape before cutting the jig.

Can I save or share my plan?

Yes. Copy shareable link puts the whole plan in the URL, so anyone who opens it sees the same beds and fabric. Print or save the plan produces a one-page summary with a beds table, totals, and the roll order.

Growing at scale

Send us the bed plan

Farms, nurseries, and landscape crews get volume pricing on SHIELD and XBAR. Share your plan link with the request and we will price the roll list for you.

Keep planning